/* $Id: ClpPrimalColumnDantzig.cpp 2385 2019-01-06 19:43:06Z unxusr $ */
// Copyright (C) 2002, International Business Machines
// Corporation and others.  All Rights Reserved.
// This code is licensed under the terms of the Eclipse Public License (EPL).

#include "CoinPragma.hpp"

#include <cstdio>

#include "CoinIndexedVector.hpp"

#include "ClpSimplex.hpp"
#include "ClpPrimalColumnDantzig.hpp"
#include "ClpFactorization.hpp"
#include "ClpPackedMatrix.hpp"

//#############################################################################
// Constructors / Destructor / Assignment
//#############################################################################

//-------------------------------------------------------------------
// Default Constructor
//-------------------------------------------------------------------
ClpPrimalColumnDantzig::ClpPrimalColumnDantzig()
  : ClpPrimalColumnPivot()
{
  type_ = 1;
}

//-------------------------------------------------------------------
// Copy constructor
//-------------------------------------------------------------------
ClpPrimalColumnDantzig::ClpPrimalColumnDantzig(const ClpPrimalColumnDantzig &source)
  : ClpPrimalColumnPivot(source)
{
}

//-------------------------------------------------------------------
// Destructor
//-------------------------------------------------------------------
ClpPrimalColumnDantzig::~ClpPrimalColumnDantzig()
{
}

//----------------------------------------------------------------
// Assignment operator
//-------------------------------------------------------------------
ClpPrimalColumnDantzig &
ClpPrimalColumnDantzig::operator=(const ClpPrimalColumnDantzig &rhs)
{
  if (this != &rhs) {
    ClpPrimalColumnPivot::operator=(rhs);
  }
  return *this;
}

// Returns pivot column, -1 if none
int ClpPrimalColumnDantzig::pivotColumn(CoinIndexedVector *updates,
  CoinIndexedVector * /*spareRow1*/,
  CoinIndexedVector *spareRow2,
  CoinIndexedVector *spareColumn1,
  CoinIndexedVector *spareColumn2)
{
  assert(model_);
  int iSection, j;
  int number;
  int *index;
  double *updateBy;
  double *reducedCost;

  bool anyUpdates;

  if (updates->getNumElements()) {
    anyUpdates = true;
  } else {
    // sub flip - nothing to do
    anyUpdates = false;
  }
  if (anyUpdates) {
    model_->factorization()->updateColumnTranspose(spareRow2, updates);
    // put row of tableau in rowArray and columnArray
    model_->clpMatrix()->transposeTimes(model_, -1.0,
      updates, spareColumn2, spareColumn1);
    for (iSection = 0; iSection < 2; iSection++) {

      reducedCost = model_->djRegion(iSection);

      if (!iSection) {
        number = updates->getNumElements();
        index = updates->getIndices();
        updateBy = updates->denseVector();
      } else {
        number = spareColumn1->getNumElements();
        index = spareColumn1->getIndices();
        updateBy = spareColumn1->denseVector();
      }

      for (j = 0; j < number; j++) {
        int iSequence = index[j];
        double value = reducedCost[iSequence];
        value -= updateBy[j];
        updateBy[j] = 0.0;
        reducedCost[iSequence] = value;
      }
    }
    updates->setNumElements(0);
    spareColumn1->setNumElements(0);
  }

  // update of duals finished - now do pricing

  double largest = model_->currentPrimalTolerance();
  // we can't really trust infeasibilities if there is primal error
  if (model_->largestDualError() > 1.0e-8)
    largest *= model_->largestDualError() / 1.0e-8;

  double bestDj = model_->dualTolerance();
  int bestSequence = -1;

  double bestFreeDj = model_->dualTolerance();
  int bestFreeSequence = -1;

  number = model_->numberRows() + model_->numberColumns();
  int iSequence;
  reducedCost = model_->djRegion();

#ifndef CLP_PRIMAL_SLACK_MULTIPLIER
  for (iSequence = 0; iSequence < number; iSequence++) {
    // check flagged variable
    if (!model_->flagged(iSequence)) {
      double value = reducedCost[iSequence];
      ClpSimplex::Status status = model_->getStatus(iSequence);

      switch (status) {

      case ClpSimplex::basic:
      case ClpSimplex::isFixed:
        break;
      case ClpSimplex::isFree:
      case ClpSimplex::superBasic:
        if (fabs(value) > bestFreeDj) {
          bestFreeDj = fabs(value);
          bestFreeSequence = iSequence;
        }
        break;
      case ClpSimplex::atUpperBound:
        if (value > bestDj) {
          bestDj = value;
          bestSequence = iSequence;
        }
        break;
      case ClpSimplex::atLowerBound:
        if (value < -bestDj) {
          bestDj = -value;
          bestSequence = iSequence;
        }
      }
    }
  }
#else
  // Columns
  int numberColumns = model_->numberColumns();
  for (iSequence = 0; iSequence < numberColumns; iSequence++) {
    // check flagged variable
    if (!model_->flagged(iSequence)) {
      double value = reducedCost[iSequence];
      ClpSimplex::Status status = model_->getStatus(iSequence);

      switch (status) {

      case ClpSimplex::basic:
      case ClpSimplex::isFixed:
        break;
      case ClpSimplex::isFree:
      case ClpSimplex::superBasic:
        if (fabs(value) > bestFreeDj) {
          bestFreeDj = fabs(value);
          bestFreeSequence = iSequence;
        }
        break;
      case ClpSimplex::atUpperBound:
        if (value > bestDj) {
          bestDj = value;
          bestSequence = iSequence;
        }
        break;
      case ClpSimplex::atLowerBound:
        if (value < -bestDj) {
          bestDj = -value;
          bestSequence = iSequence;
        }
      }
    }
  }
  // Rows
  for (; iSequence < number; iSequence++) {
    // check flagged variable
    if (!model_->flagged(iSequence)) {
      double value = reducedCost[iSequence] * CLP_PRIMAL_SLACK_MULTIPLIER;
      ClpSimplex::Status status = model_->getStatus(iSequence);

      switch (status) {

      case ClpSimplex::basic:
      case ClpSimplex::isFixed:
        break;
      case ClpSimplex::isFree:
      case ClpSimplex::superBasic:
        if (fabs(value) > bestFreeDj) {
          bestFreeDj = fabs(value);
          bestFreeSequence = iSequence;
        }
        break;
      case ClpSimplex::atUpperBound:
        if (value > bestDj) {
          bestDj = value;
          bestSequence = iSequence;
        }
        break;
      case ClpSimplex::atLowerBound:
        if (value < -bestDj) {
          bestDj = -value;
          bestSequence = iSequence;
        }
      }
    }
  }
#endif
  // bias towards free
  if (bestFreeSequence >= 0 && bestFreeDj > 0.1 * bestDj)
    bestSequence = bestFreeSequence;
  return bestSequence;
}

//-------------------------------------------------------------------
// Clone
//-------------------------------------------------------------------
ClpPrimalColumnPivot *ClpPrimalColumnDantzig::clone(bool CopyData) const
{
  if (CopyData) {
    return new ClpPrimalColumnDantzig(*this);
  } else {
    return new ClpPrimalColumnDantzig();
  }
}

/* vi: softtabstop=2 shiftwidth=2 expandtab tabstop=2
*/
